With higher integration of semiconductor devices representative of large scale integrated circuits (LSIs), dynamic random access memories (DRAMs), flash memories and the like, miniaturization of circuit patterns and structures formed in a manufacturing process have been advanced. A substrate processing apparatus that performs one step of a process of manufacturing a semiconductor device is subjected to regular maintenance to maintain the performance of a substrate processing apparatus.
However, changes in the exhaust characteristics of a substrate processing apparatus may result in non-uniformity of the substrates.